This invention relates to a method of and an apparatus for producing a seat cushion member by laminating a sheet of decorative surface material, a sheet of usual or untreated polyurethane foam material and a reinforcing web of fabric material into an integral three-layer structure without the use of a welding material or an adhesive, and it relates also to a product thereby obtained.
An inexpensive seat cushion member may be produced by welding a sheet of decorative surface material, a sheet of usual or untreated polyurethane foam material and a reinforcing web of fabric material into an integral structure by a high-frequency welder. However, it has been difficult to commercially produce such an inexpensive seat cushion member due to the fact that the untreated polyurethane foam material would not be fused at the temperature of high-frequency dielectric heating by the high-frequency welder. It has therefore been a common practice to employ a sheet of treated resin foam material such as so-called weldafoam or a sheet of low-melting-point polyurethane foam material, which is expensive but has appreciable weldability, in lieu of the inexpensive sheet of untreated polyurethane foam material, or to impregrate the untreated polyurethane foam material with a welding material such as nylon in powder form, and then, to weld these three layers together by the high-frequency welder.
The products produced according to the prior art practice have however been defective in that the three layers constituting the products are insufficiently or unstably welded together and the costs of the products are inevitably high due to the fact that the weldafoam or the low-melting-point polyurethane foam material are not fully satisfactory in their weldability although they are expensive, and an impregnating equipment and operators for operating the equipment are also required for the impregnation of the untreated polyurethane foam material with the welding material such as powdery nylon.